NSW man traded drugs for gun before death

Moments after two friends were chased into a Sydney shed, one was knocked out and the other was never seen again, a murder trial has heard.

Ronald Byrnes told the jury he was punched in the face by a man with a "footballer's build" and when he gained consciousness he lay still, saw the shed was covered in blood, and heard male voices.

"I heard them say 'is that all he's got?' and 'get him in the car he's still f***ing breathing'," Mr Byrnes told the NSW Supreme Court on Friday.

Jamie Michael Tilley, 36, and Jack Davies, William Patrick Thomas and Mitchell James Bentley, all aged 27, have pleaded not guilty to kidnapping and murdering Brendan Vollmost, 23, at South Windsor in March 2015.

They also deny assaulting Mr Byrnes and a neighbour.

The jury has seen CCTV footage from outside Mr Vollmost's home showing him, and Mr Byrnes, running through a gate towards the back shed.

The pair were inside the shed when Mr Byrnes said he was punched in the face by a man and when he regained consciousness he lay still and heard men talking about taking a body out to the car.

The CCTV footage shows Mr Vollmost's body being carried out by two men.

A significant amount of his blood was found in the shed but his body has never been found.

Mr Byrnes said before his disappearance, Mr Vollmost told him a sawn-off shotgun in his shed was to protect him from the Blood Brothers.

Mr Byrnes said he had lived in Mr Vollmost's South Windsor house for about a month before the night of March 31 and admitted he was a regular user of ice and would drive Mr Vollmost around to deliver drugs.

Mr Byrnes told the jury when he first noticed the shotgun Mr Vollmost told him "they (Blood Brothers) were coming to get him".

Cameras were installed around the property with wireless monitors in the shed for security reasons, the witness said.

Under cross-examination by Davies' lawyer Phillip Young SC, Mr Byrnes agreed Mr Vollmost was worried about the safety of his girlfriend, who had a "temperamental" ex-partner, and his brother, who was about to be released from prison.

"But also about them," he added, while gesturing towards the four men in the dock.

On the evening of March 3, Mr Byrnes said he, Mr Vollmost and another friend, Brendan Knight, were in a car when they were followed by a white Hyundai leading the panicked trio to drive back to Mr Vollmost's home.